Among the variety of electronic packages used in the electronics industry, glob top BGA packages are one of the popular packages for low-end performance applications. Glob top BGA packages are part of a large family of wirebond BGA packages. These wirebond BGA packages utilize low-cost organic material based substrates (a.k.a. laminates) such as Bismaleimide triazine epoxy (“BT”), polyimide, and polytetrafluoroethylene, and are well-suited for the low-end performance applications because of their relatively low cost.
FIG. 1 illustrates a cross-sectional view of such a prior art glob top BGA package. The package consists of a laminate substrate 10 having on one side BGA solder balls 20 and on the opposite side a die attach pad (“DAP”) 14 for receiving an IC device (a.k.a. a die) 30. DAP 14 is typically surrounded by metallized wirebond pads 12 on laminate substrate 10 to which wirebond wires 34 can be bonded.
An IC device 30 is attached to DAP 14 using thermally conductive epoxy 32 with its active side facing away from laminate substrate 10. Wirebond wires 34 make the electrical interconnection between IC device 30 and metallized pads 12 on laminate substrate 10. One end of each wirebond wire 34 is bonded to a wirebond pad (not shown) on the IC device and the other end of the wire is bonded to a pad 12. The side of laminate substrate 10 where IC device 30 is attached is then encapsulated with glob top epoxy 40 which is dispensed in sufficient amount to cover IC device 30 and wirebond wires 34. Glob top epoxy 40 is dispensed in a liquid state and then cured. Glob top epoxy 40 protects IC device 30 and wirebond wires 34 against corrosion and mechanical damage.
Although these prior art wirebond BGA packages have relatively poor cooling capability, they have been adequate because IC devices used in low-end performance applications have been relatively low powered. Typical power dissipation of IC devices used in this performance segment up to now has been about 3 Watts.
With ever-increasing integration of the IC devices driven by the demand for higher performance, IC devices at all levels of application have been incorporating more circuits per unit area. With every new generation of IC devices, this development has resulted in increases in both the performance and the power output of each device. This trend has also resulted in the utilization of higher performing and higher powered IC devices in the low-cost application segment where glob top BGA packages are commonly used. Therefore, there is a need for low-cost wirebond BGA packages with improved cooling capabilities that can accommodate IC devices with greater than 3 Watts of power dissipation.